Chapter 1

What is Science? Process that tries to explain how events in nature occur Defined as systematic process of inquiry

Biology Science of life Studies organisms – complete and entire living things

Characteristics of organisms All organisms are made up of cells Cells – basic unit of life Organism can be one cell or millions of cells Unicellular – organism made of one cell Why is a virus not a cell?

Characteristics Continued Organisms reproduce Process by which organisms make more of their own Necessary or there would be extinction But it is not necessary that all organisms reproduce Two kinds of reproduction Asexual reproduction – no joining of cells, one parent, no variations in offspring Sexual reproduction – joining of two cells, two parents, variations in offspring

Characteristics Continued Organisms have metabolism – total sum of all chemical activities in an organism Organisms must obtain and use energy to grow, move, and process information Two kinds of metabolic activity: Anabolic – activities that build materials, such as photosynthesis, protein synthesis Catabolic – activities that tear down substances, such as digestion, cellular respiration

Characteristics Continued Organisms maintain homeostasis – steady state of balance Organisms respond to changing conditions internally & externally Organisms respond so that they can maintain homeostasis How do we maintain homeostasis of our body temperature?

Characteristics Continued All living things exhibit heredity – passing of traits from parents to offspring This is done through genes – basic unit of heredity – section of DNA Mutation – changes in DNA, can be harmful or helpful Example: sickle cell anemia If mutation is in a sex cell – harm to offspring If mutation is in a body cell – harm to individual

Characteristics Continued Evolution – change in the inherited traits of a species over time Species – group of similar organisms that can mate and produce fertile offspring Fertile – able to reproduce Some members of a species have differences called variations These variations make them survive better and produce more offspring So species changes gradually over time Natural selection – organisms with favorable genes are more likely to survive and reproduce

Characteristics Continued Interdependance Organisms in a biological community live and interact with each other Ecology – branch of biology that studies the interactions of organisms with one another and with the nonliving part of their environment.

Branches of Biology: Cytology – study of cells Genetics – study of heredity Evolution – study of changes in organisms over time Ecology – study of how organisms effect each other and their environment Microbiology – study of small organisms Taxonomy – study of the classification of organisms

Branches of Biology: Anatomy – study of the structures of organisms Physiology – study of how the structures of organisms work Paleontology – study of extinct organisms Botany – study of plants Zoology – study of animals Ethology – study of animal behavior

Occupations that require Biology Doctor, nurse, vet, marine biologist, physical therapist, dietician, pharmaceutical representative, farmer, landscape designers, dentist, dental hygienist, eye doctor (these are just a few of the many careers in the field of Biology)

Scientific Method To find out how things work, scientists use the scientific method Scientific method is defined as a logical and orderly way to solve a problem

Steps: Observe and state the problem Form a hypothesis. Hypothesis – educated guess Test the hypothesis 2 setups for this: control & experimental Only difference between them – variable Independent variable – factor that is changed from the control to the experimental groups Dependent variable – factor that is measured in the experiment Record & analyze data. (Refer to page 9 table & graph) Form a conclusion Be able to replicate your work. Take clear notes as you work

Hypothesis: Is tested and confirmed by others becomes a theory – time-tested concepts that make useful and dependable predictions about the natural world

The metric system Science works best when scientists everywhere read each other’s papers, check each other’s experiments and agree about what those experiments mean. To do this a universal system of measurements is needed. The metric system is used and the universal system of measurements. It is called the International System of Units or the SI. It is based on multiples of 10 which makes it easier to use than the English system. (Refer to table of page 11)

Metric Units: Length – how long an object is. The basic unit of length in the metric system is the meter (39.4 inches). Centimeters or millimeters are used for small objects. Kilometers are used for longer distances. Centi means 1/100 or one-hundredth Milli means 1/1000 or one-thousandth Kilo means 1000

Metric Units: Volume – amount of space an object occupies. The basic unit of volume in the metric system is the liter. It is a little more than a quart. Milliliters are used to measure small amounts of liquid Cubic centimeters (cm³) is used to measure the volume of solid objects. Displacement in water is used to measure solid, irregular objects Length x width x height is used to measure the volume of regular, solid objects. 1 ml = 1 cm³ = 1 cc

Metric Units: Mass – measure of amount of matter in an object Weight – measure of the pull of gravity on an object On Earth, mass and weight are usually the same and used interchangeably. Basic unit of mass in the metric system is the kilogram. Grams are used to measure the mass of small objects

Metric Units: Temperature is measured in degrees Celsius. On the Celsius scale: Boiling point of water = 100 Freezing point of water = 0 Room temperature = 21 Body temperature = 37

Tools of the Biologist: Microscope – used to enlarge an image Kinds: Compound light microscope – has 2 lenses that work together along with light to produce a visible, enlarged image Magnification – enlargement of an image Resolution – production of a clear image Light is the energy source Two lenses are located in the eyepiece and the objective To determine the magnification of the microscope: magnification of the eyepiece x magnification of the objective Limitation of the light microscope: The greater the magnification, the less resolution. This means the larger the image is the less clear id is.

Tools Continued Electron microscope – uses a beam of electrons as the energy source Has tremendous magnification – up to 200,000x However, living materials cannot be used due to the way that materials have to be prepared to be used in the electron microscope Two kinds of electron microscope Transmission electron microscope (TEM) Used to view the internal structures. Done in a vacuum. The image is projected onto a screen Scanning electron microscope (SEM Use to view the 3-D surface of an object. Object is coated with a metal

Tools Continued Scanning tunneling microscope needle-like probe to measure differences in voltage caused by electrons that leak from the surface of an object being viewed Produces a 3-D image of surface